Whi is Blue is the novel, Wayward Son?

Blue is the water creature that Shepard visits at the Hoover Dam. She appreciates that he gives her several items, including a book and a radio, and she recognizes Simon as the person who drained the magic (in the previous novel of this series) and then gave it back. Blue would like to be set free and asks Shepard to consider her request to blow up the dam.